Solar Hot Water Installation with EdenSol

SOLAR SO GOOD

With rising fuel prices and environmental issues solar hot water heating is now becoming a hot subject. There are many people jumping on the bandwagon and over selling the products for hugely inflated prices. We have heard of specialist companies selling systems for £12,000 with predictions of a six year pay back. Add to this the credit deal buy now pay later and any other nonsense such as service contracts and you will never see a return on your investment inside 20 years. Even with a predicted 40% rise in fuel prices over the next few years the payback period on solar could still be ten years depending on how expensive your plumber is. Solar certainly shouldn't be top of the list in energy saving investments but once you have insulated your cavity walls, improved your draught proofing and changed to a high efficiency (HE) condensing boiler then solar hot water is well worth considering, especially if you are changing your hot water cylinder anyway. If you can do some of the work yourself then you are beginning to enter the bright sunlit uplands.

The basic choice of collectors is between evacuated tubes and flat plate panels. The tubes are more efficient so they take up less room for a given output. Panels are less efficient so you need more square metres but they are cheaper and more robust. Some people will tell you that by the time a solar hot water system has been paid for the panels will need replacing. They may well be just out of their guarantee period but that doesn't mean they are on their last legs. There is no reason why they should last for twenty years which puts you very firmly into profit. For most people though the payback period is not the compelling reason for fitting panels and just breaking even is an acceptable result. If you sell your home then the solar hot water heating will add value.

PRACTICAL CONSIDERATIONS

A south facing aspect is the number one requirement. You can get away with South East to South West but due south is the best. That way you will get a high yield from the panels even in the winter. Try to position the cylinder close to the panel but also close to the bathroom and kitchen. Keeping pipe runs to a minimum is an important energy saving factor. Cylinder manufacturers are missing a trick by not making hot water cylinders which can be laid down on their side in an eaves cupboard.

This would save space but also keep the cylinder close to the panels and it would be ideal for loft conversions. If you are a cylinder manufacturer and you decide to do this don't forget to send me a cheque. When running pipework between the panel and cylinder it would be nice to think that you could simple snake a couple of lengths of plastic pipe down to the cylinder but unfortunately this is not possible due to the very high temperatures created by the panel. It was even considered at one time that solder fittings would soften and blow apart if the temperatures got too hot. This might be the case directly next to the panel where compression fittings are preferred but there are many installations with solder fittings and I have yet to hear of one where this has resulted in a failure. Nevertheless it is not advisable to use ordinary pipe insulation, plastic pipe clips or any fittings containing 'O' rings. This rules out push fit fittings.

SAFETY

Such high temperatures are also likely to cause scalding if there is no control to the taps. A thermostatic mixing valve which blends cold with hot water as it leaves the cylinder will prevent scalding and effectively increase the capacity of your cylinder by drawing less hot water. Such valves are now readily available and may soon be a legal requirement on all cylinders but make sure you buy one which is specifically designed for solar cylinders because lower grade valves often have plastic components which will soften to syrup in the higher temperatures.

The panels and pipework are filled with a heat transfer liquid (antifreeze) which also helps prevent corrosion. Much like car radiators this should not need topping up in a sealed system. The system needs to be sealed rather than open vented because water boils at 100cent in atmospheric pressure (1 bar) and boiling water cannot be pumped. It would also evaporate making your loft into a Turkish bath.

We hope the information here is useful to you. Further information is available through the manufacturer’s links and our forum is open to you for further specific information about your individual requirements. And if you are going up on the roof (or in a cherry picker) take care. No solar heating is worth a broken neck. If you aren't confident and comfortable at heights stay on the ground.